Feed device for conveyor belts loaded with pick-and-place components

ABSTRACT

A feed device is for a conveyor belt loaded with pick-and-place components. The feed device includes at least one transport wheel which can be coupled with the conveyor belt to move the conveyor belt, and a drive device coupled with a transport wheel. The transport wheel is provided with a control mechanism whose input shaft and output shaft cross.

[0001] This application is the national phase under 35 U.S.C. § 371 ofPCT International Application No. PCT/DE01/03640 which has anInternational filing date of Sep. 20, 2001, which designated the UnitedStates of America and which claims priority on German patent applicationnumber DE 100 48 458.1 filed Sep. 29, 2000, the entire contents of whichare hereby incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The invention generally relates to a feed device for conveyorbelts loaded with pick and place elements or components. Preferably, itrelates to one having at least one transport wheel and a drive devicecoupled to the latter.

BACKGROUND OF THE INVENTION

[0003] Electronic components are, for example, provided arranged onconveyor belts. The conveyor belts are conventionally provided with atop layer which prevents the components falling off the conveyor belt.In order to be able to pick the components, for example arranged on theconveyor belt, and place them on a printed circuit board, the top layermust be removed. By this, the components are gradually liberated, inorder to be removed from the conveyor belt and placed on a printedcircuit board via a handling device, such as a pick and place head of apick and place apparatus.

[0004] Since the components are becoming smaller and smaller and alreadycurrently have very small dimensions, it is necessary to position theconveyor belt with the components arranged thereon correspondinglyaccurately. For this purpose, use has hitherto been made of feed deviceswhich, for example, first transported the conveyor belt forward, pullingoff the top layer and liberating the components, and then positioned theconveyor belt accurately by use of a mechanical stop, against which thedrive device had moved the transport wheel or the mechanism used tocouple the drive device to the transport wheel. In this case, however,jolting movements of the conveyor belt occur, as a result of which thecomponents can fall off the conveyor belt before they can be removedfrom the conveyor belt by the pick and place head of the pick and placeapparatus.

[0005] In order to prevent the components falling off the conveyor belt,a hold-down apparatus for the components has been used. This held thecomponents in the pockets in the conveyor belt until the components wereremoved via a pick and place head. However, the hold-down apparatusmeant a great deal of mechanical expenditure, and was susceptible todefects and slows down the feed cycle of the pick and place elements.Furthermore, in conventional feed devices, the jolting movements of theconveyor belt are undesired, since pick and place elements can fall offthe conveyor belt in spite of the hold-down apparatus.

SUMMARY OF THE INVENTION

[0006] There is therefore the need for a feed device by which exactpositioning and feeding of conveyor belts loaded with pick and placeelements is simply and reliably possible.

[0007] According to an embodiment of the invention, a feed device forconveyor belts loaded with pick and place components is provided whichhas at least one transport wheel and a drive device coupled to thelatter. The transport wheel can be coupled to the conveyor belt in orderto move it. Furthermore, the transport wheel is provided with a controlmechanism whose input shaft and output shaft cross. This achieves thesituation where the control mechanism is self-locking, so that, via thecontrol mechanism, the movement of the drive device and therefore themovement of the transport wheel which drives the conveyor belt can becontrolled.

[0008] The control mechanism can be, for example, a worm gear mechanismor a screw gear mechanism. A worm gear mechanism of this type can have aworm gear which is formed on the transport wheel and through which theoutput shaft runs, and a control spindle which engages in the worm gearand through which the input shaft runs.

[0009] Furthermore, a control apparatus can be provided by which themovement of the transport wheel driven by the drive device can becontrolled by use of the control mechanism. The control apparatus canhave a control drive which is coupled to the control mechanism and fromwhich power can be taken or power can be output via a control shaft.

[0010] The control drive can be an electrical drive. This makes itpossible, by use of an electronic control apparatus, to use suitablecontrol methods for controlling the movement of the transport wheel.

[0011] The control shaft of the control drive can coincide with theinput shaft of the control mechanism. For example, the control shaft ofthe control drive can be connected directly to the control spindle ofthe control mechanism. This permits a reduced requirement for space forthe control drive and the control mechanism.

[0012] Furthermore, the drive device of the transport wheel can becoupled to the transport wheel via a drive spindle which, in addition tothe control spindle, engages in the worm gear of the control mechanism.A further reduction in overall size is made possible by this.

[0013] By way of the control apparatus, the rotational speed and/or thepower of the control drive can be controlled as a function of therotational speed and/or the power of the drive device.

[0014] The control drive can furthermore be controllable by way of thecontrol apparatus as the drive of the transport wheel. This makes itpossible to drive the transport wheel both with the drive device of thetransport wheel and with the control apparatus via the controlmechanism. In this case, higher power outputs to the transport wheel andtherefore faster transport of the conveyor belt are possible than if thetransport wheel were driven only by the drive unit.

[0015] The transport wheel can be provided with an encoder in order toregister its position, and the feed device can have a sensor, by whichthe encoder can be sensed.

[0016] The drive device and the control drive are preferably constructedidentically. In this way, the construction of the feed device accordingto an embodiment of the invention and its design and development aresimplified and benefited.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The invention will be explained in more detail with reference tothe drawings, in which:

[0018]FIG. 1 shows a schematic plan view of a preferred embodiment ofthe invention, and

[0019]FIG. 2 shows a graph which reveals a course of a voltage appliedto a drive device and a control drive of the preferred embodiment of theinvention as a function of the rotational speed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] As FIG. 1 reveals, the preferred embodiment of the invention hasa transport wheel 100, a control drive 200-1 and a drive device 200-2.The drive device 200-2, the control drive 200-1 and the transport wheel100 are arranged on a base plate 300. The transport wheel 100 has aplurality of transport pins 105, which are formed distributed on thecircumference of the transport wheel 100 and are used to engage intransport openings which are formed in the conveyor belt, which can betransported by the feed device according to an embodiment of theinvention. The transport wheel 100 is also provided with a worm gear150. A control spindle 250-1 and a drive spindle 250-2 engage in theworm gear 150. The control spindle 250-1 is connected to the controldrive 200-1 via a control shaft 210-1.

[0021] A bearing 220-1 for the control shaft 210-1 is provided on thebase plate 300. The drive spindle 250-2 is connected to the drive device200-2 via an input shaft 210-2. A bearing apparatus 220-2 for the inputshaft 210-2 is provided on the base plate 300.

[0022] The simultaneous engagement of the control spindle 250-1 and thedrive spindle 250-2 in the worm gear 150 makes it possible to constructthe feed device according to an embodiment of the invention with verysmall dimensions in the axial direction. As a result, the feed deviceaccording to an embodiment of the invention is particularly suitable fornarrow conveyor belts.

[0023] The control drive 200-1 and the drive device 200-2 can, forexample, be constructed identically, so that if required the controldrive 200-1 can be used to drive the transport wheel 100 in addition tothe drive device 200-2.

[0024]FIG. 2 reveals a graph of an example of a course of the voltageswhich are applied to the control drive 200-1 and the drive device 200-2as a function of the rotational speed. As can be seen from FIG. 2, themagnitude of that voltage which is applied to the drive device 200-2 ishigher by a constant difference than the magnitude of the voltage whichis applied to the control drive 200-1.

[0025] Thus, as the transport wheel 100 is driven, the driving actionvia the drive device 200-2, the input shaft 210-2, the drive spindle250-2 and the worm gear 150 is provided without play, since the drivedevice 200-2 is supplied with more energy than the control drive 200-1,by which any play possibly present between the drive spindle 250-2 andthe worm gear 150 or the control spindle 250-1 and the worm gear iscompensated for.

[0026] However, it is also possible to use a different relation betweenthe power and/or the rotational speed of the control drive and the powerand/or the rotational speed of the drive device 200-2. For example, thecontrol drive 200-1 and the drive device 200-2 can be supplied with thesame power or operated at the same rotational speed, so that it ispossible to drive the transport wheel 100 with twice the drive power.

[0027] At a changeover from drive operation to positioning operation, itis possible to switch over to the aforementioned different supply ofdrive device 200-2 and control drive 200-1, so that play-freepositioning of the transport wheel 100 and thus of the conveyor beltwhich holds the components is possible.

[0028] The transport wheel 100 can be provided with an encoder 121, forexample with a lined disc. The encoder 121 can be sensed by use of asensor 122. The sensor 122 can be connected to the control apparatus, bywhich highly accurate positioning of the transport wheel 100 andtherefore of a conveyor belt coupled to the latter is then possible.Furthermore, by use of the encoder 121 together with the sensor 122 andthe control apparatus, it is possible to control the movement of thetransport wheel 100 highly accurately in a closed control loop.

[0029] The invention being thus described, it will be obvious that thesame may be varied in many ways. Such variations are not to be regardedas a departure from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1. A feed device for conveyor belts loaded with pick and placecomponents having at least one transport wheel (100), which can becoupled to a conveyor belt in order to move the conveyor belt, and adrive device (200-2) coupled to the transport wheel (100), characterizedin that a control mechanism (250-1, 150) is provided on the transportwheel (100) and has an input shaft and an output shaft which cross. 2.The feed device as claimed in claim 1, characterized in that the controlmechanism (250-1, 150) is a worm gear mechanism, which has a worm gear(150) which is formed on the transport wheel (100) and through which theoutput shaft runs, and a control spindle (250-1) which engages in theworm gear (150) and through which the input shaft runs.
 3. The feeddevice as claimed in claim 1 or 2, characterized in that the movement ofthe transport wheel (100) driven by the drive device (200-2) can becontrolled by a control apparatus that is operatively connected to thecontrol mechanism (250-2, 150).
 4. The feed device as claimed in claim3, the control apparatus having a control drive (200-1) which is coupledto the control mechanism (250-1, 150) and from which power can be takenor power can be output via a control shaft (210-1).
 5. The feed deviceas claimed in claim 4, the control drive (200-1) being an electricdrive.
 6. The feed device as claimed in either of claims 4 and 5,characterized in that the control shaft (210-1) of the control drive(200-1) coincides with the input shaft of the control mechanism (250-1,150).
 7. The feed device as claimed in one of claims 1 to 6,characterized in that the drive device (200-2) is coupled to thetransport wheel (100) via a drive spindle (250-1) which engages in theworm gear (150) of the control drive (250-1, 150).
 8. The feed device asclaimed in one of claims 3 to 7, characterized in that the controlapparatus is able to control the rotational speed and/or the power ofthe control drive (200-1) as a function of the rotational speed and/orthe power of the drive device (200-2).
 9. The feed device as claimed inclaim 8, characterized in that the control apparatus is able to controlthe control drive (200-1) as the drive of the transport wheel (100). 10.The feed device as claimed in one of claims 1 to 9, characterized inthat the transport wheel (100) has an encoder (121) and the feed deviceis provided with a sensor (122) for sensing the encoder (121).
 11. Thefeed device as claimed in one of claims 4 to 10, the drive device(200-2) and the control drive (200-1) being constructed identically.